The security issues are the major consideration while implementing Mobile Ad hoc Networks (MANETs). Misbehavior of any node can do serious implications in this kind of dynamic network. A malicious or selfish node wants to preserve own resources along with using the services of other nodes and consumed their resources. Malicious nodes can break the rules and reduce the performance of well-behaved nodes significantly. This paper describes the different attacks and analysis of within Network Layer in MANETs.

1. IJSRD - International Journal for Scientific Research & Development| Vol. 1, Issue 9, 2013 | ISSN (online): 2321-0613
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A Review Paper on Network Layer attacks in MANETs
Dhruvi Marsonia1
Prof. Hardik Patel2
1
P. G. Student (I. T.) 2
Assistant Professor
1
Shantilal Shah Engineering College, Bhavnagar, Gujarat
2
Sir Bhavsinhji Polytechnic Institute, Bhavnagar, Gujarat
Abstract—The security issues are the major consideration
while implementing Mobile Ad hoc Networks (MANETs).
Misbehavior of any node can do serious implications in this
kind of dynamic network. A malicious or selfish node wants
to preserve own resources along with using the services of
other nodes and consumed their resources. Malicious nodes
can break the rules and reduce the performance of well-
behaved nodes significantly. This paper describes the
different attacks and analysis of within Network Layer in
MANETs.
Key words: MANETs, Ad Hoc, Security, Robust, Malicious
nodes, selfish node etc.
I. INTRODUCTION TO MANETS
The MANET is the collection of mobile users that
communicate over relatively bandwidth constrained wireless
links. Since the nodes are mobile, the network topology may
change speedily and random over time. It is also known as
infrastructure less network. MANETs can form stand-alone
groups of wireless terminals, but some of these may be
connected to some fixed network. Compared to wireless
networks in infrastructure mode ad-hoc networking doesn't
require any access points. This makes useful in lots of
different applications. It is largely used in military
applications and in rescue operations where the existing
communication infrastructure has been destroyed is possible
for two nodes which are not in the communication range of
each other, but still can send and receive data from each
other with the help of intermediate nodes which can act as
routers. This functionality gives another name to ad hoc
network as “multi-hop wireless network”. There are
different routing attacks which appear in network layer
during wireless transmission of messages. These attacks are
caused by either some internal or external intruders. To
accomplish our goal, we have done some methods to
gathering information related to various types of attacks and
solutions. In this paper we have study different attacks in
network layer and also some security issue in mobile ad-hoc
network.
II. VULNERABILITY OF MANETS
In a network Vulnerability of Manets is a weakness in
security system. A particular system may be vulnerable to
unauthorized data manipulation because the system does not
verify a user’s identity before allowing data access. MANET
is weaker than wired network. Some of the vulnerabilities
are as follows:
Lack of centralized management:A.
MANET doesn’t have a centralized monitor server. The
absence of centralized management makes the detection of
attacks difficult because it is not east to monitor the traffic in
a highly dynamic and large scale ad-hoc network. Lack of
centralized management will impede trust management for
nodes [1].
Dynamic Topology:B.
In MANETs, nodes can join and leave the network
dynamically and can move independently. Due to such type
nature there is no fixed set of topology works in MANETs.
The nodes with poor physical protection may become
malicious node and reduce the network performance [2].
Resource availability:C.
Resource availability is a major issue in MANET. Providing
secure communication in such changing environment as
well as protection against specific threats and attacks, leads
to development of various security schemes and
architectures. Collaborative ad-hoc environments also allow
implementation of self-organized security mechanism [1].
Limited resources:D.
The MANETs consists of different set of devices such as
laptops, computers, mobile phones etc. All of such devices
having different storage capacity, processing speed,
computational power etc. This may attracts the attackers to
focus on new attacks [2].
Scalability:E.
Due to flexibility of nodes, scale of ad-hoc network
changing all the time. So scalability is a major issue about
security. Security mechanism should be capable of handling
a large network as well as small ones [1].
Cooperativeness:F.
Routing algorithm for MANETs usually assume that nodes
are cooperative and not a malicious. As a result a malicious
attacker can easily become an important routing agent and
interrupt network operation by violating the protocol
specifications [1].
Limited power supply:G.
The nodes in mobile ad-hoc network need to consider
restricted power supply, which will cause several problems.
A node in mobile ad-hoc network may behave in a selfish
manner when it is finding that there is only limited power
supply [1].
Wireless Links:H.
As the nodes in such networks are interconnected through
wireless interface that makes it highly susceptible to link
attacks. The bandwidths of wireless networks are less as
compared to wired networks, which attracts many attackers
to prevent normal communication among nodes [2].

2. A Review Paper on Network Layer attacks in MANETs
(IJSRD/Vol. 1/Issue 9/2013/0011)
All rights reserved by www.ijsrd.com 1738
III. SECURITY ATTACKS
Securing wireless ad-hoc networks is a highly challenging
issue. Understanding possible form of attacks is always the
first step towards developing good security solutions.
Security of communication in MANET is important for
secure transmission of information [9]. Absence of any
central co-ordination mechanism and shared wireless
medium makes MANET more vulnerable to digital/cyber-
attacks than wired network there are a number of attacks
that affect MANET. These attacks can be classified into two
types.
Types
of
Attack
Characteristics Example
Passive
Attacks
Obtains information without
disturbing normal network
operation
• Difficult to detect
Traffic analysis,
traffic
monitoring and
eavesdropping
Active
Attacks
Can be internal (attacker
within the network) or
external (attacker outside the
network)
•Can disturb network
operation by modifying or
deleting information,
injecting a false message or
impersonating a node
Modification,
Impersonation,
jamming and
message replay
Table. 1: Attack Classification
Passive attacksA.
Passive attacks are the attack that does not disrupt proper
operation of network .Attackers watch data exchanged in
network without altering it. Detection of passive attacks is
difficult since the operation of network itself does not get
affected. Different type of passive attack as follow:
1) Release of Message Content
Release of Message Content is like an Eavesdropping.
Secretly listening to the private conversation of others
without their consent
2) Traffic Analysis
Traffic analysis is Monitoring or observes a situation for any
changes which may occur over time.
Active attacksB.
Active attacks that are performed by the malicious nodes
that bear some energy cost in order to perform the attacks.
Active attacks include some modification of data stream or
creation of false stream. Active attacks, whether carried out
by an external advisory or an internal compromised node
involves actions such as impersonation (masquerading or
spoofing), modification, fabrication and replication.
Different types of Active attacks are as follow:
1) Masquerade
Masquerade is Pretend to be someone one is not. For
example bob does not send a message to Alice. But Darth
send a message to Alice as that appears by the bob.
2) Replay
Reply is Pretend to Playing again. For Example Bob send a
message to Alice but that message capture by Darth and
latter reply message to Alice.
3) Modification of Messages
Modification of messages is to Alteration in original
message. Some Modification in message as like some data
insertion, deletion, modification etc. Message is altered,
deployed to produce an unauthorized effect.
4) Denial of Service
Denial of service is an attempt to make a resource
unavailable to its intended users.
Some of the Dos Attacks are also listed below.
IV. NETWORK LAYER ATTACKS
Layer Example Of Attacks
Network Layer
DoS attacks: Wormhole, Black hole,
Gray hole, Byzantine, Resource
Consumption attack, Rushing attack
Information Disclosure
selfishness Attack: selfish node
.malicious node
Table. 2: Network Layer Attacks.
Network Layer AttacksA.
1) Wormhole Attack:
In this attack two compromised nodes create a tunnel or
wormhole hole that linked through a private connection and
thus they by-pass the network. This allows the node to short-
circuit the normal flow of routing that control by the two
attackers [5].The Wormhole attack is a kind of tunneling
attack which is extremely dangerous and damaging to
defend against even though the routing information is
confidential, authenticated or encrypted [4]. It is relatively
easy to deploy but exceedingly hard to detect. Usually
Wormhole attack is launched by two malicious nodes
(worms) connected via a high-speed wired or wireless link
called Wormhole link or tunnel. Nodes outside each other’s
communication range have to communicate via intermediate
nodes in a multi-hop way. [4]. The worms can drop
delivered messages and acquire statistical data of traffic by
investigating message traffic [10]. To minimize delay, the
attacker may forward each bit through the Wormhole link
without waiting for the entire packet to be received [4].
 Operation of Wormhole Attack:
As shown in Figure 1, two malicious nodes X and Y created
the Wormhole attack on the MANET. X and Y are
connected via a high-speed Wormhole link that tunnels
traffic between nodes A and B. when node A want to
communicate with node B, normally it takes multiple hops
for a packet to travel between them. Though in the
attendance of worms X and Y, A and B start believing that
they are immediate neighbors. Packets traveling through
Wormhole link travel faster to the destination than packets
traveling through multiple hops in the MANET. X and Y do
not alter the packet header and falsify the route lengths.
Packets received by X are replayed through Wormhole link
to Y and vice versa. X and Y can now selectively drop data
packets or analyze traffic and disrupt the network’s
communication. Malicious nodes X and Y along with the
Wormhole link are not visible in the route; and also the
Wormhole attacker is hidden from the higher layers.
Therefore, detection of Wormhole attack is exceedingly
tough.

3. A Review Paper on Network Layer attacks in MANETs
(IJSRD/Vol. 1/Issue 9/2013/0011)
All rights reserved by www.ijsrd.com 1739
Fig. 1: wormhole Attack
2) Packet Dropping or Black-hole Attack:
Blackhole attack is another type of DoS attack. In mobile ad
hoc networks (MANETs), nodes usually cooperate and
forward each other’s packets in order to enable out of range
communication. Saving their own resources or for
intentionally disrupting regular communications. This type
of misbehavior is generally referred to as packet dropping
attack or black hole attack [6].That generates and
disseminates fabricated routing information. If the malicious
node replies to the requesting node before the actual node
replies, a bogus route will be created. Therefore packets are
not forwarded to the specified destination node; instead, the
malicious node intercepts the packets, drops them and thus,
absorbs network traffic [4].
 Operation of Blackhole Attack:
An example of Blackhole attack against AODV protocol
(Ad-hoc On demand Distance Vector) is shown in Figure 2.
[4]. Suppose source S wants to communicate with node D. S
initiates route discovery process by broadcasting route
request packets (RREQ) to its neighbors. The destination
node D or any intermediate nodes having fresh route to the
destination can give reply by sending reply packet (RREP)
to S. Considering no intermediate nodes have a fresh route
to D, they forward request packets towards destination. As
X is a malicious node, it doesn’t forward the request packet
ahead; instead, it falsely replies to S indicating that it has a
valid fresh route to D. Thus, reply packet from X reaches to
S ahead of reply packets from other neighbors of S.
Therefore, S considers sending packets to D via X
considering that X has a shortest route to D. Now X absorbs
all packets forwarded from S to D. This is how a Blackhole
attack is setup.
Fig. 2: Blackhole attack
3) Gray-hole attack:
This attack is also known as routing misbehaviour attack
which leads to dropping of messages. Gray hole attack has
two phases. In the first phase the node advertise itself as
having a valid route to destination while in second phase,
nodes drops intercepted packets with a certain
probability[1].Grayhole attack is an extension of Blackhole
attack in which a malicious node’s behavior is exceptionally
unpredictable[4].
4) Resource Consumption Attack:
In this attack, a malicious node intentionally tries to
consume the resources (e.g. battery power, bandwidth etc)
of other nodes in the network. The attack can be of various
types like unnecessary route requests, route discovery,
control messages, or by sending stale information [6].
5) Selfishness Attack:
Cooperation among nodes in Ad- Hoc Networks is an
important issue for communication. But some nodes do not
cooperate in communication and saves their energy. These
nodes are called Selfish nodes. Selfish nodes participate in
route discovery stage properly to update their routing table,
but as soon as data forwarding stage begins, they drop data
packets This malicious node which is not participating in
network operations, use the network for its advantage to
save its own resources such as power [6, 1].
a) Selfish Misbehavior of Nodes
Attacks under this category, are directly affects the self-
performance of nodes and does not interfere with the
operation of the network [2]. It may include two important
factors.
i) Protection of battery power
ii) Gaining partial share of bandwidth: The selfish nodes
may reject to take part in the forwarding process or drops
the packets purposefully in order to conserve the
resources. These attacks use the routing protocol to their
own advantage. Packet dropping is one of the main
attacks by selfish node which indications to congestion
in network. However most of routing protocols have no
mechanism to detect whether the packets being
forwarded or not except DSR (dynamic source routing)
[2].
b) Behavior of Malicious nodes
The main of malicious node is to disrupt normal operation
of routing protocol. The impact of such attack is increased
when the communication takes place between neighboring
nodes. Attacks of such type are fall into following
categories.
i) Denial of Service (DOS): These types of attacks
produced a malicious action with the help of
compromised nodes that forms severe security risks. In
the presence of compromised nodes, it is very difficult to
detect the compromised routing. The compromised route
appears like a normal route but leads to severe problems.
For example, a compromised node could participate in
the communication but drops some packets which lead to
degradation in the quality of service being offered by
network [2].
ii) Attacks on Network integrity: Network integrity is an
important issue, in order to provide secure
communication and quality of service in network. There
are so many threats which exploit the routing protocol to
introduce wrong routing information [2].
iii) Misdirecting traffic: A malicious node advertises wrong
routing information in order to get secure data before the

4. A Review Paper on Network Layer attacks in MANETs
(IJSRD/Vol. 1/Issue 9/2013/0011)
All rights reserved by www.ijsrd.com 1740
actual route. These nodes receive information that was
intended for owner of the address. A malicious node may
advertise fake route request, so that other nodes will then
direct route replies to the node [2].
iv) Attacking neighbor sensing protocols: malicious nodes
advertise fake error messages so that important links
interface are marked as broken. This will result in
decrease in network throughput and quality of service
[2].
 Operation of malicious nodes
In such attacks, the attackers can create routing loops to
form severe congestion. Different type of attacks are
identified which are initiated by malicious node. The
malicious node “X” can absorb important data by placing
itself between source “A” and destination “D” as shown in
Figure-3. “X” can also divert the data packets exchanged
between “A” and “D”, which results in significant end to
end delay between “A” and “D”. In this type of attacks
attackers attacks against Routing and Path Selection The
malicious node can disrupt the route discovery process by
creating routing loops and overflow routing tables [2].
Fig. 3: Malicious nodes
V. CONCLUSION AND FUTURE WORK
Due to dynamic structure of MANETs and having no
centralized administration, it makes it more vulnerable to
many attacks. It is discussed, the weakness MANETs as
well as various active and passive attacks. (There is no
significant contribution has been shown in work means what
is your finding and what are the solutions)
In future study we will try to invent such intrusion
detection system with routing protocols that helps to reduce
the impact of different attacks.
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